Our SPORE has been instrumental in establishing that promoter region DMA hypermethylation, and attendant abnormal gene silencing, play a key role in the development and progression of human cancer, in general, and lung cancer, in particular. During the past funding cycle, we markedly moved this concept to a highly translational arena in terms of lung cancer management through a synthesis of studies. These include discovery of new genes aberrantly methylated in lung cancer and defining their position and biological function in the progression of the disease. Most importantly, we now have defined the utility of a panel of promoter region DMAmethylation markers as a robust potential molecular system for re-staging stage I NSCLC to stage III disease. During the last funding period, we performed a blinded, retrospective, nested case control study of 167 patients who underwent curative surgery for stage I lung cancer (51 cases who recurred within 40 months; 116 controls who did not recur). The finding that 2 or more DMA hypermethylated genes in tumor plus histologically tumor-free mediastinal nodes can predict recurrent disease with odds ratios up to 25-fold, constitutes a new paradigm for the molecular staging of lung cancer. The significance of these discoveries has important implications which will be explored in the current proposal. Silencing of the gene markers represent not only prognostic markers, but also serve as a potential target for a unique new adjuvant approach for stage I non-small cell lung cancer (NSCLC) using epigenetic therapy to re-express the silenced genes. To prepare for this, we have started a prospective study of resected stage I lung NSCLC to validate our above work indicating that changes in DNA methylation can predict disease recurrence and death. We will also use newly discovered changes in promoter methylation to improve this molecular test. To prepare for use of epigenetic therapy adjuvant approaches, we will continue an already initiated Phase 2 trial of epigenetic therapy with inhibitors of DNAmethylation and histone deacetylases, in which a major response has already been achieved. Finally we will initiate an adjuvant trial with these agents, to determine if targeting epigenetic changes improves the disease free and overall survival of patients with resected lung cancer. Successes, here will suggest prevention strategies as well. Relevance to Public Health: Lung Cancer is responsible for the greatest number of cancer deaths in the United States and other western countries. Effective treatment of early stage lung cancer would result in improvements in survival and reduction in death from lung cancer. Our studies should help define which patients with early lung cancer are at highest risk for disease recurrence after surgery, and therefore need additional therapy. In addition, we will determine whether therapy directed at these changes proves effective in reducing disease recurrence.